Field of the Disclosure
The present disclosure relates to a torsional vibration damper that reduces a torsional vibration resulting from a pulsation of an inputted torque.
Discussion of the Related Art
Up to now, there is known a torsional vibration damper in which a torsional vibration resulting from a torque pulse is reduced by a reciprocating motion (pendulum motion) of a mass body (refer to JP-A-2017-145857, for example). This kind of damper includes: a rotating body inputted with a torque; an inertia body that rotates relatively to the rotating body due to the torque fluctuation; and a coupling member that couples the rotating body and the inertia body in a manner enabling torque transmission. Moreover, a first coupling section is formed on either one of the rotating body and the inertia body. The first coupling section restricts the coupling member in a rotating direction of the rotating body and engages the coupling member movably in a radial direction of the rotating body. Furthermore, a second coupling section is formed on the other one of the rotating body and the inertia body. The second coupling section engages with the coupling member. When the rotating body and the inertia body rotate relatively, a place of contact on the first coupling section of the coupling member undergoes displacement in the radial direction of the rotating body, whereby the coupling member engages in the first coupling section and the second coupling section.
In the previously mentioned torsional vibration damper, downsizing and increasing a mass of the mass body to improve attenuation performance of low frequency vibration, are desired. In FIG. 15 described in JP-A-2017-145857, there is described an embodiment having a configuration in which two inertia bodies have been arranged on both sides of the rotating body. In that embodiment, each of the inertia bodies has formed therein two coupling sections (raceway surfaces) against which the coupling member (rolling member) is pressed by a centrifugal force due to the rotating body rotating. The second coupling section is configured as an arc surface of a certain radius of curvature centered on a place deviating from a rotational center of the rotating body. In this kind of damper, it is desired to increase a mass of the coupling member to improve attenuation performance of low frequency vibration.
Increasing of mass for improving attenuation performance with respect to low frequency vibration is, in short, to increase an inertia moment of the inertia body or coupling member. In the damper described in JP-A-2017-145857, since two inertia bodies of the same size are used, the mass overall of the inertia body gets larger. However, in the configuration described in JP-A-2017-145857, by increasing the number of inertia bodies, the damper ends up increasing in size. That is, up to now, there has been room for improvement in increasing the inertia moment to improve vibration attenuation performance with respect to low frequency vibration without causing an increase in size of the damper.